Compressor unit, heat source unit, and air conditioner

ABSTRACT

A compressor unit for an air conditioner includes a compressor disposed in a first casing, and first and second heat source heat exchanger unit ports configured to connect the compressor unit to a heat source heat exchanger of a heat source heat exchanger unit of the air conditioner, the heat source heat exchanger being disposed in a second casing separate from the first casing and being configured to exchange heat with a heat source, first and second indoor unit ports configured to connect the compressor unit to an indoor heat exchanger of at least one indoor unit of the air conditioner, a first refrigerant piping fluidly connecting the first heat source heat exchanger unit port and the first indoor unit port, and a sub-cooling heat exchanger disposed inside the first casing and fluidly connected to the first refrigerant piping for heat transfer with the refrigerant to be flown through the first refrigerant piping.

TECHNICAL FIELD

The present invention relates to air conditioners and particularly air conditioners using outside air or circulating water as heat source. Such air-conditioners may as well be called heat pumps. Further, the air-conditioners may be used for cooling and/or heating of a space to be conditioned. More particularly, the present invention relates to a compressor unit for such an air conditioner and a heat source unit of such an air conditioner.

BACKGROUND ART

Generally speaking, air-conditioners consist of one or more outdoor units and one or more indoor units connected via a refrigerant piping. The outdoor and indoor units each comprise a heat exchanger for, on the one hand, exchanging heat with the heat source and, on the other hand, exchanging heat with the space to be conditioned. Outdoor units of air-conditioners are in most cases installed outside a building for example on the roof or at the facade. This, however, has under certain circumstances being perceived disadvantageous from an aesthetical point of view. Therefore, EP 2 108 897 A1 suggested to integrate the outdoor unit into a ceiling of the building so as to be hidden therein and not to be noticeable from the outside of the building.

Yet, the outdoor unit suggested in this document has certain disadvantages. One negative aspect is that the outdoor unit produces noises which may be perceived disturbing by individuals inside the building. A second negative aspect is installation and maintenance, because the outdoor unit is relatively heavy and because of its construction requires a relatively large installation space with respect to its height.

CITATION LIST Patent Literature

PTL 1: EP 2 108 897 A1

SUMMARY OF INVENTION Technical Problem

To overcome these drawbacks, the applicant of the present application has considered splitting the heat source unit into a compressor unit and a heat source heat exchanger unit. Further, some appliances require the integration of a sub-cooling section into the refrigerant circuit to increase efficiency. Yet, the integration of a sub-cooling section into a splitted heat source unit may require more piping between the heat source heat exchanger unit and the compressor unit as well as the indoor unit leading to a more complicated installation and higher installation costs. In addition, more piping through which gaseous refrigerant flows is required. Such piping is more expensive due to a larger required diameter and hence more material. Moreover, more time is necessary for installation. Finally, a loss of effect may be recognized if the piping for gaseous refrigerant between the compressor unit and the heat source heat exchanger unit becomes too long. The above disadvantages have been recognized when disposing the sub-cooling heat exchanger close to the heat source heat exchanger, i.e. in the heat source heat exchanger unit.

Solution to Problem

Accordingly, one object the present invention intends to solve is to provide a compressor unit, preferably as part of the above-described heat source unit, as well as a heat source unit having such a compressor unit, which are capable of reducing the piping and particularly the piping for gaseous refrigerant for connecting the several units to a minimum even if a sub-cooling section is integrated, thereby ensuring ease of installation and lower installation costs.

This object is solved by a compressor unit according to claim 1 or a heat source unit according to claim 5. Embodiments of the invention are named in the dependent claims, the following description and the accompanying drawings.

According to one aspect, a compressor unit for an air conditioner is suggested. The air-conditioner is configured to condition a space such as a room inside the building, be it heating or cooling. The compressor unit comprises a compressor disposed in a first casing. Accordingly, the first casing is accommodating the compressor and preferably encapsulating the compressor. Additionally, a sound insulation may be provided at the inside or outside of the casing to avoid noises produced by the compressor from being transferred to the environment in which the compressor unit is installed. Further, a first and second heat source ports are provided and preferably accessible from the outside of the casing for ease of connection. The first and second heat source ports are configured to connect the compressor to a heat source heat exchanger of a heat source unit of the air conditioner by means of a refrigerant piping. The first and second heat source ports may be of any kind capable of connecting a refrigerant piping to the compressor such as a pipe open at one end and having an outer thread at the end. Yet, also so-called self-sealing connectors or quick fasteners may be used. In most cases it will however due to regulations be required to use flairs or braised connections. The heat source heat exchanger is disposed in a second casing separate from the first casing and configured to exchange heat with a heat source. “Separate” in this context means that the casings represent separate assemblies or units and should not encompass that one casing is disposed within the other casing. In a particular embodiment, the heat source heat exchanger unit uses outside air (i.e. air outside the building) as heat source. For this purpose, it is preferred that the second casing has a first connection at one side of the heat exchanger and a second connection at an opposite side of the heat exchanger. The first and second connections are preferably connected to ducting fluidly communicated with the outside of the building so that outside air may pass the first heat exchanger. Moreover, the compressor unit comprises a first and second indoor unit ports configured to connect the compressor to an indoor heat exchanger of at least one indoor unit of the air conditioner by refrigerant piping. The first and second indoor unit ports may be of the same or different kind as the first and second heat source ports. Further, the compressor unit comprises a first refrigerant piping preferably disposed within the first casing. The first refrigerant piping fluidly connects the first heat source port and the first indoor unit port. Accordingly, the first heat source port and the first indoor unit port are used to fluidly connect the heat source heat exchanger unit to one or more indoor units using refrigerant piping. Even though the connection between the heat source heat exchanger unit and the indoor unit/-s could be made to direct, one aspect suggests to connect these units via the compressor unit so that part of the refrigerant piping connecting these units passes through the first casing of the compressor unit. Furthermore, a sub-cooling heat exchanger is disposed inside the first casing and fluidly connected to the first refrigerant piping for sub-cooling refrigerant to be flown through the first refrigerant piping. Because the first refrigerant piping is passing through the first casing, the sub-cooling heat exchanger may be integrated into the air conditioner without an additional gaseous refrigerant piping being necessary to connect the compressor unit and the heat source heat exchanger unit and particularly the heat source heat exchanger and the suction side of the compressor passing the sub-cooling heat exchanger. This additional long gaseous refrigerant piping is integrated into the compressor unit and therefore much shorter so that less material is required and less installation time necessary. Therefore, ease of installation is obtained and the installation costs are reduced.

According to an embodiment the compressor unit further comprises a second refrigerant piping. The second refrigerant piping fluidly communicates or connects the second heat source port and the second indoor unit port. The compressor and preferably a 4-way valve are interposed between the second heat source port and the second indoor unit port or more particular in the second refrigerant piping connecting these ports. An accumulator may be included on the suction side of the compressor. Moreover, a bypass passage is connected to the second refrigerant piping at the suction side of the compressor between the compressor and the 4-way valve and the sub-cooling heat exchanger is fluidly connected to the bypass passage for heat transfer between the refrigerant flowing in the bypass line and refrigerant flowing through the first refrigerant piping. Hence, all piping relating to the sub-cooling unit is a contained in the first casing so that in one embodiment only four ports are required in the compressor unit. To connect the compressor unit, the heat source heat exchanger unit and one indoor unit. In particular, an additional route between the heat source heat exchanger unit and the indoor unit can be avoided by placing the sub-cooling heat exchanger in the compressor unit and looping the refrigerant piping connecting the heat source heat exchanger module to the indoor unit through the compressor unit. An additional advantage of disposing the sub-cooling heat exchanger in the compressor module is that a large diameter pipe usually required to flow the gaseous refrigerant can be avoided.

According to an aspect, the compressor unit does not comprise a main expansion valve of the air conditioner. The “main expansion valve” of an air conditioner is defined as that expansion valve through which the entire amount of refrigerant in the refrigerant circuit passes during cooling.

In heating the main expansion valve defines the superheat after the heat source heat exchanger. In cooling the main expansion valve is always fully opened to avoid a high pressure drop. In cooling the entire amount of refrigerant passes the main expansion valve. In heating, the amount of refrigerant is separated between the flow through the sub-cooling heat exchanger and the heat source heat exchanger.

In heating operation, a relatively large pressure drop exists because of a relatively long refrigerant piping connecting the sub-cooling heat exchanger to the heat source heat exchanger. Because the main expansion valve is not disposed in the compressor unit, a refrigerant pressure drop between the compressor unit and the heat source heat exchanger unit can be can be compensated and two phase flow noise is reduced.

According to an embodiment, the compressor unit may comprise an oil separator located at the discharge side of the compressor between the compressor and a (the) 4-way valve.

According to another aspect a heat source unit for an air conditioner is suggested which comprises the above-described compressor unit and a heat source heat exchanger unit. The heat source heat exchanger unit has a heat source heat exchanger disposed in the second casing separate from the first casing as described above. The heat source heat exchanger is configured to exchange heat with a heat source particularly outside air and is fluidly connected or communicated to the compressor unit via the first and second heat source port. In this context, and because of the connection of the first heat source port and the first indoor unit port by the first refrigerant piping the connection of the heat source heat exchanger unit and the indoor unit is looped through the compressor unit (first casing). Thereby, it is possible to integrate the sub-cooling unit into the compressor unit without an additional piping required to connect the compressor unit with the heat source heat exchanger unit.

As described previously, the main expansion valve of the air conditioner is disposed in the second casing, i.e. in the heat source heat exchanger unit. Accordingly, the pressure drop between the compressor unit and the heat source heat exchanger unit is kept as low as possible and two phase flow noises can be avoided.

As previously indicated, one or more indoor units can be fluidly connected or communicated to the compressor unit via the first and second indoor unit port. This context, the first indoor unit port serves for the connection of the indoor unit and particularly an indoor heat exchanger to the heat source heat exchanger unit and particularly the heat source heat exchanger. The second indoor unit port serves to connect the indoor unit and particularly the indoor heat exchanger to the second refrigerant piping and, hence, the compressor. If more than one indoor unit is provided, the indoor units can be connected in parallel.

Further features and effects of the heat source unit may be obtained from the following description of embodiments. In the description of these embodiments reference is made to the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a schematic circuit diagram of an air conditioner,

FIG. 2 a schematic sketch of the air conditioner shown in FIG. 1 installed in a building,

FIG. 3 shows a perspective view of a heat source heat exchanger unit,

FIG. 4 shows a perspective view of a compressor unit,

FIG. 5 shows a longitudinal section of the heat source heat exchanger unit of FIG. 3, and

FIG. 6 shows a schematic circuit diagram of an air conditioner according to a variation of the configuration shown in FIG. 1.

DESCRIPTION OF EMBODIMENTS

FIG. 1 shows the circuit diagram of an air conditioner. The air-conditioner has a heat source unit 30 comprising a heat source heat exchanger unit 31 and a compressor unit 32.

The heat source heat exchanger unit 31 comprises a heat exchanger 5 which consists of an upper heat exchanger element 6 and a lower heat exchanger element 7 which are positioned relative to each other to form the shape of a “V” in a side view or cross sectional view (see FIG. 5). The heat source heat exchanger unit 31 further comprises the main expansion valve 33 of the refrigerant circuit. As becomes apparent from FIG. 1, the entire amount of refrigerant contained in the circuit also passes the main expansion valve 33 during cooling. In other words, the entire amount of refrigerant delivered or supplied from the compressor 37 flows through the main expansion valve 33 during cooling.

The heat source heat exchanger unit is also shown in more detail in FIGS. 3 and 5.

FIGS. 3 and 5 show a heat source heat exchanger unit 31 which may be part of the heat source unit 30.

The heat source heat exchanger unit 31 comprises a casing 2 (second casing) being configured for connection to an outside air duct of an air conditioner. In particular, the heat source heat exchanger unit is configured as an “outdoor” unit of an air conditioner which is, however, disposed inside particularly within the ceiling of a building. Hence, a first connection 3 is provided at the casing 2 for connection to an air duct communicating the heat source heat exchanger unit 31 with the outside of the building and so as to enable taking of outdoor air into the casing 2. A connection 4 (See FIG. 5), provided for the connection of the heat source heat exchanger unit 31 to the air duct again leading to the outside of the building and to enable exhausting of air having passed the heat exchanger 5 to the outside, is disposed at the opposite end of the casing 2.

The casing 2 is substantially rectangular and flat, meaning that the height H is a smaller than the width W and the length L. In one embodiment the height H is not more than 50 cm, preferably not more than 45 cm, more preferred not more than 40 cm and most preferred not more than 35 cm.

The heat source heat exchanger unit 31 further comprises a heat exchanger 5 (heat source heat exchanger) which is also visible in FIG. 3. However, the configuration of the heat exchanger 5 can be best seen from FIG. 5. FIG. 5 also represents a side view of the heat exchanger 5 in the sense of the present application.

The heat exchanger 5 comprises an upper heat exchanger element 6 and a lower heat exchanger element 7. Both, the upper and lower heat exchanger elements 6, 7 are flat or planar shaped and are positioned with an angle α enclosed between them. As best visible from FIG. 1, the upper and lower heat exchanger elements 6, 7 are fluidly connected in parallel to the refrigerant piping. Hence the heat exchanger 5 has a V-shape wherein the “V” is oriented horizontally. A line CL passing the apex 8 of the “V” is oriented horizontally, that is along the length L extension of the heat source heat exchanger unit 31. The line CL is also the centerline of the heat exchanger 5 or to put it differently a line of symmetry as regards the heat exchanger elements 6, 7.

The heat exchanger 5 is arranged within the air duct formed by the casing 2 so that all air sucked in through the opening at the connection 3 has a to flow through the heat exchanger 5 without any air bypassing the heat exchanger 5 at the top or the bottom or the sides of the heat exchanger 5 in the width direction W.

The upper and lower heat exchanger elements 6, 7 are connected to each other at the apex 8 by a connecting element 9. The connecting element is impermeable to air and also used to mechanically or physically connect the upper and lower heat exchanger elements 6, 7. Each of the heat exchanger elements 6, 7 comprises heat exchanger coils 10 (loops of tubing) and fins 11 disposed there between. The heat exchanger of the present embodiment is applied for outdoor applications, i.e. as part of the heat source unit of an air conditioner. In this case, the fins of the upper and lower heat exchanger element 6, 7 are preferably waffled fins. Even though louvered fins are preferably used for a good air flow through the heat exchanger as several holes are provided to allow the air to flow through the fins, condensation water may accumulate in these holes and may lead to problems regarding the formation of frost during heating operation, when the ambient temperature is lower than about 7 degrees Celsius. To prevent these problems it is in these cases preferred to use waffled fins.

Two backward curved centrifugal fans 20 are provided inside the casing. These backward curved centrifugal fans 20 each have a suction opening 21. In the side view (FIG. 5), the center axis of the suction opening 21 and hence the fans 20 is substantially congruent or aligned with the center line CL of the heat exchanger 5. In some appliances, it may however be sufficient as in the depicted embodiment that the center axis of the suction opening 21 and the centerline CL of the heat exchanger 5 are parallel but displaced relative to each other in a horizontal direction.

In use, the fans 20 create a suction force at the suction opening 21 so as to induce a fluid flow (airflow) in the direction F. Thus air, particularly outside air is drawn in through the connection 3 toward the open end 12 of the heat exchanger 5, passes through the upper and lower heat exchanger elements 6, 7 and is sucked through the suction opening 21 to be flown out through the connection 4. As such the casing 2 defines a duct from the connection 3 via the heat exchanger 5 and the fan 20 to the connection 4. In this context, the connection 3 and the connection 4 define an inlet opening 13 and an outlet opening 14.

Furthermore, a drain pan 15 is provided within the casing. The drain pan 15 is separated into two halves 16, 17 along the length L of the casing 2 in the side view. In FIG. 5, the two halves 16, 17 are identified by the dotted line with one half being located on the left side and one half being located on the right side of the dotted line. The drain pan 15 has a lowest position 18 at which a drain opening 19 is provided. The bottom of the drain pan 15 slants toward the drain opening 19 and hence the lowest position 18. Thus water dropping from any component into the drain pan is directly guided to the drain opening 19 and the lowest position 18 which is furthest away from the fan 20. Thereby it is prevented that water accumulated within the drain pan may be sucked into the fan 20 and hence through the opening 14 into the duct. The drain opening 19 is directly connected to drainage so that water is directly drained.

Moreover, a sound and/or thermal insulation 22 are provided within the casing 2 at the side opposite to the drain pan 15 with respect to the line CL. In the cross section and hence a side view (FIG. 5), the inner surfaces of the drain pan 15 and the insulation 22 respectively directed to the heat exchanger 15 should be approximated so that the duct created within the casing 2 is as symmetric as possible.

Further, the distance between the apex 8 and the entry of the suction opening 21 should be as short as possible to reduce the length. In particular, the high velocity zone of the fans should in the side view not overlap with the heat exchanger 5 and/or the drain pan 15.

At a side of the casing 2, one can see a first and second refrigerant piping connection 34 and 35 for connecting the heat source heat exchanger unit 31 to the refrigerant piping of the refrigerant circuit. In addition a connection port 36 for connecting the drain opening 19 to drainage (not shown) extends from the same side surface of the casing 2 as the refrigerant piping connections 34 and 35.

The casing 2 is completely closed relative to the environment except for the connections 3 and 4 as well as the refrigerant piping connections 34 and 35 and the connection 36 to the drainage. Accordingly and as can be seen from FIG. 5 the casing may be sound insulated and thereby encapsuled to prevent any noises for example from the fans from being transferred to the space to be conditioned. In addition and because the compressor 37 is not disposed in the casing 2 but the compressor unit 32 as described below, no noise of the compressor is induced and transferred via the air flowing through the heat source heat exchanger unit 31 and in the air duct connected to the outside of the building.

The compressor unit 32 has a casing 44 (First casing) wherein in FIG. 4 a front wall of the casing 44 and a corresponding sound insulation have been removed to partly show the interior of the casing 44. A compressor 37 (see FIG. 1) is disposed in the casing 44. Furthermore, all other components of the compressor unit described below and if present will be disposed in the casing 44 as well. In addition, the compressor unit may comprise an optional accumulator 38 and a 4-way valve 39.

In addition, the compressor unit 32 comprises a sub-cooling heat exchanger 40 and a sub-cooling expansion valve 41. The sub-cooling heat exchanger is a tube heat exchanger.

The compressor unit 32 further comprises first and second refrigerant piping connections 42 and 43 (first and second heat source heat exchanger unit ports) as shown in FIG. 4.

A stop the valve 45 (two stop valves, one for each connection 42, 43) may be provided close to the first and second refrigerant piping connections 42 and 43, respectively.

Further a third and fourth refrigerant piping connection 46 and 47 (first and second indoor unit ports) are provided for connection of one or more indoor units 50 (one in the present embodiment) disposed in fluid communication with the space to be conditioned. A stop valve 48 (two stop valves, one for each connection 46, 47) is also provided close to the refrigerant piping connections 46 and 47, respectively.

Ports 42, 43 and 46, 47 are all disposed close to the front of the compressor unit to improve serviceability. In particular, if the front wall of the casing 44 and the corresponding insulation is removed as in FIG. 4, the ports are easily accessible.

Moreover, a refrigerant piping 80 (second refrigerant piping) connects the refrigerant piping connection 42 and the refrigerant piping connection 47 with the 4 way valve 39, the compressor 37, the accumulator 38, the connection 81 to the refrigerant piping 57, the connection 82 to the refrigerant piping 52 and the 4-way valve 39 being interposed in this order.

The aforesaid components are disposed in the following order from the refrigerant piping connection 47 to the refrigerant piping connection 42 considering cooling operation (solid arrows in FIG. 1): the 4-way valve 39, the accumulator 38, the compressor 37, the 4-way valve 39 and the refrigerant piping connection 42. The aforesaid components are disposed in the following order from the refrigerant piping connection 42 to the refrigerant piping connection 47 considering heating operation (broken arrows in FIG. 1): the 4-way valve 39, the accumulator 38, the compressor 37, the 4-way valve 39 and the refrigerant piping connection 47.

Furthermore, a refrigerant piping 49 connects the first refrigerant piping connection 43 and the third refrigerant piping connection 46. The sub-cooling heat exchanger 40 is configured to exchange heat between the refrigerant flowing in the refrigerant piping 49 and the refrigerant flowing in the refrigerant piping 52. A sub-cooling expansion valve 41 is disposed in the refrigerant piping 52 between the sub-cooling heat exchanger and the refrigerant piping connection 43. To put it differently, the sub-cooling expansion valve 41 is disposed between the connection of the refrigerant piping 52 with the refrigerant piping 49 and the sub-cooling heat exchanger 40. In any case and during heating and cooling operation, the sub-cooling expansion valve 41 is disposed upstream of the sub-cooling heat exchanger 40 in the refrigerant piping 52.

A refrigerant piping 51 connects the accumulator 38 and the 4-way valve 39. Even further, a refrigerant piping 52 (gaseous refrigerant piping) connects at one end to the refrigerant piping 49 and at the other end to the refrigerant piping 51. Further, a refrigerant piping 57 connects the refrigerant piping 49 and the refrigerant piping 51 with a pressure regulating valve 58 being integrated into the refrigerant piping 57 at an intermediate position.

The casing 44 of the compressor unit 32 may be sound insulated so that noise produced by the compressor 37 can be prevented from exiting the casing and disturbing individuals inside the building. Further, the casing 44 can because of its compact size be disposed on the floor for easy installation and maintenance and even below a cupboard of a kitchen or other technical equipment rooms. The casing 44 may additionally comprise feet 59 as shown in FIG. 4 for placing and fixing the casing 44 on a horizontal supporting surface. The size of the casing 44 particularly relating to its height, widths and depth complies with DIN EN 1116 for kitchen furniture and kitchen appliances.

An example of an indoor unit 50 comprises an indoor heat exchanger 53 (second heat exchanger) connected respectively via third and fourth refrigerant piping connections 54 and 55 and a refrigerant piping to the third and fourth refrigerant connections 46 and 47 of the compressor unit 32. Optionally, the indoor unit 50 may comprise an indoor expansion valve 56 disposed between the indoor heat exchanger 53 and the third refrigerant piping connection 54. The indoor unit 50 may in principle be configured as a common indoor units used in such air-conditioners.

As can be best seen from FIG. 2, the air conditioner may be installed in a building 70. In one possible embodiment, the heat source heat exchanger unit 31 can be disposed in the ceiling 71 of a space 72 to be conditioned and being hidden within the ceiling 71. The connections 3 and 4 are preferably connected to an air duct 73 so that the casing 2 of the heat source heat exchanger unit 31 forms part of the air duct 73. The end of the air duct 73 opens at both ends 74 and 75 to the outside of the building so that outside air may be sucked in through the end 74 passes the heat exchanger 5 of the heat source heat exchanger unit 31 and is exhausted through the end 75.

The heat source heat exchanger unit 31 is connected by refrigerant piping 76 to the compressor unit 32 using the refrigerant piping connections 34 and 35 as well as 43 and 42, respectively. The compressor unit 32 again is connected to the indoor unit/-s 50 via refrigerant piping 77 using the third to fourth refrigerant piping connections 46, 47 and 54, 55 respectively.

The operation of the air conditioner described above is as follows. During cooling operation (solid arrows in FIG. 1), refrigerant flows into the compressor unit 32 at the refrigerant piping connection 47 passes the 4-way valve 39 and is introduced into the accumulator 38. When passing the accumulator associate liquid refrigerant is separated from the gaseous refrigerant and liquid refrigerant is temporarily stored in the accumulator 38.

Subsequently, the gaseous refrigerant is introduced into the compressor 37 and compressed. The compressed refrigerant is introduced into the heat source heat exchanger unit 31 via the first refrigerant piping connections 42, 35 and a refrigerant piping 71. The refrigerant passes the heat exchanger 5 with its plates 6, 7 of the heat source heat exchanger unit 31, whereby the refrigerant is condensed (the heat exchanger 5 functions as a condenser). Hence, heat is transferred to the outside air parallely passing through the heat exchanger elements 6, 7 of the heat exchanger 5. The expansion valve 33 is entirely opened to avoid high pressure drops during cooling. Then, the refrigerant flows into the compressor unit 32 via the third refrigerant piping connections 34, 43 and refrigerant piping. In the compressor unit 32, the refrigerant flows in part through the refrigerant piping 52 and, hence, the sub-cooling expansion valve 41 and the sub-cooling heat exchanger 40 and in part through the refrigerant piping 49 being introduced via the third refrigerant piping connection 46, a refrigerant piping and the third refrigerant connection 54 into the indoor unit 50. The refrigerant is then further expanded by the indoor expansion valve 56 and evaporated in the heat exchanger 53 (the heat exchanger 53 functions as evaporator) cooling the space 72 to be conditioned. Accordingly, the heat is transferred from air in the space to be conditioned to the refrigerant flowing through the heat exchanger 53. In cooling the main purpose of the sub-cooling heat exchanger 40 is to sub-cool the liquid refrigerant flowing through the refrigerant piping 49 to the indoor unit 50. Finally, the refrigerant is again introduced via the fourth refrigerant piping connections 55, 47 and refrigerant piping into the compressor unit 32.

As is generally known, the capacity of an air conditioner at the indoor side is the multiplication of enthalpy and mass flow. Hence a reduced mass flow may be used when the enthalpy is increased. The sub-cooling heat exchanger serves to increase enthalpy at the indoor side. As a consequence, the mass flow can be reduced without impairing capacity. As a result the pressure drop in the liquid pipe can be reduced so that the compressor 37 needs to deliver less work improving the entire system efficiency.

During heating, this circuit is reversed wherein heating is shown by the broken arrows in FIG. 1. The process is in principle the same. Yet, the first heat exchanger 5 functions as evaporator whereas the second heat exchanger 53 functions as condenser during heating. In particular, refrigerant is introduced into the compressor unit 32 via the first refrigerant piping connection 42, flows via the 4-way valve 39 into the accumulator 38 and is then compressed in the compressor 37 before flowing into the 4-way valve 39 and through the fourth refrigerant piping connections 47, 55 and refrigerant piping into the indoor unit 50 and particularly the indoor heat exchanger 53 where the refrigerant is condensed (the indoor heat exchanger 53 functions as a condenser). Subsequently, the refrigerant is expanded by the expansion valve 56 and then reintroduced via the third refrigerant piping interconnections 54, 46 into the compressor unit 32 where the refrigerant flows into the piping 49 and passes the sub-cooling heat exchanger 40.

By refrigerant injection after the evaporator, the suction superheat before the compressor can be optimized. As a result, the discharge temperature can be reduced with the beneficial effect of better efficiency of the system and prolonged lifetime. In heating, the sub-cooling heat exchanger 40 serves to improve the refrigerant quality at the compressor inlet via the refrigerant piping 52 connected to the refrigerant piping 51 upstream of the compressor 37, that is on the suction side of thereof. Further, the sub-cooling heat exchanger 40 serves to evaporate the two phase refrigerant in the refrigerant piping 49 as desired.

Subsequently, part of the refrigerant flows into the refrigerant piping 52, is expanded in the sub-cooling expansion valve 41 and flows through the sub-cooling heat exchanger 40 before being reintroduced into the refrigerant piping 51 upstream of the accumulator 38 thereby pre-cooling the refrigerant flowing through the refrigerant piping 49 passing the sub-cooling heat exchanger 40. The remaining part flows into the heat source heat exchanger unit 31 via the second refrigerant piping connections 43 and 34 and refrigerant piping. The refrigerant is further expanded by the main expansion valve 33 in the heat source heat exchanger unit 31 and then evaporated in the heat exchanger 5 (the heat exchanger 5 functions as evaporator) before being reintroduced into the compressor unit 32 via the first refrigerant piping connections 35 and 42 and refrigerant piping.

Because of the splitting of the compressor unit 32 and the heat source heat exchanger unit 31, the compressor unit 32 may be installed in areas that are not noise sensitive so that there is no noise disturbance caused by the compressor even though disposed indoors. In addition the casing 44 of the compressor unit 32 may be well insulated with sound insulation. Even further, there is no compressor noise in the air flowing through the heat source heat exchanger unit 31 due to the split concept between the heat source heat exchanger unit 31 and the compressor unit 32 which could be transferred into the space to be conditioned.

Because of the lower weight per unit of the heat source heat exchanger unit 31 and the compressor unit 32, the installation is improved. In addition, the compressor unit 32 may be installed on the floor so that there is no need to lift the heavy compressor unit. Because of a relatively small footprint (width and depth) of the compressor unit 32 and a lower height of the compressor unit 32 and particularly its casing 44, the compressor unit 32 may even be hidden when disposed inside the room to be conditioned such as below a cupboard or counter-board.

The heat source heat exchanger unit 31 has also the advantage that there is no noise disturbance. Because the compressor is not contained in the heat source heat exchanger unit 31 the only sound that can be entrained in the airstream is the noise of the fan whereby the noise in the airstream is drastically reduced. Further, the casing 2 can be entirely closed to the space 72 to be conditioned so that no sounds are transferred into the space. Also this casing may be well insulated with sound insulation. Because of the lower height of the heat source heat exchanger unit 31, it is easy to hide the unit for example in the ceiling. Therefore, the unit 31 is not visible from the outside. The installation is also improved because of the lower weight as compared to units having the compressor in the same casing and because of the lower height of the heat source heat exchanger unit 31. The lower height is particularly assisted by using the “V” shape of the heat exchanger 5, which enables high-efficiency with a relatively low height.

Because of the integration of the sub-cooling unit particularly the sub-cooling heat exchanger into the compressor unit rather than the heat source heat exchanger unit, one long gaseous refrigerant piping connecting the heat source heat exchanger with the suction side of the compressor can be substituted by a shorter line 52 contained in the compressor unit. Hence, a large diameter pipe usually required to flow the gaseous refrigerant can be shortened. In other words, an additional route between the heat source heat exchanger unit and the indoor unit can be avoided by placing the sub-cooling heat exchanger in the compressor unit and looping the refrigerant piping connecting the heat source heat exchanger module to the indoor unit through the compressor unit.

If the sub-cooling heat exchanger was disposed in the heat source heat exchanger module and the fluid connection between the units 31 and 50 would not be looped through the casing 44 of the compressor unit 32, but directly connected, a third heat source heat exchanger port was necessary at the compressor unit 32 with an additional line connecting the compressor unit 32 and the heat source heat exchanger unit 31 to implement the line 52. The present embodiment is hence improved as compared to this case with a consequence of easier installation and lower installation costs.

Moreover, because the main expansion valve 33 is disposed in the heat source heat exchanger unit 31, the refrigerant pressure drop caused by a relatively long refrigerant piping between the compressor unit 32 and the heat source heat exchanger unit 31 can be compensated and two phase flow noise can be reduced to at least some extent.

FIG. 6 shows the circuit diagram of an air conditioner according to a variation of the configuration shown in FIG. 1. The difference between the configurations in FIG. 1 and FIG. 6 is the use of a heat source heat exchanger module 31′ that is configured to utilize water heat source.

The air-conditioner according to this variation has a heat source unit 30 comprising a heat source heat exchanger unit 31′, a cooling tower 90, and a compressor unit 32. The heat source heat exchanger unit 31′ operates in cooperation with the cooling tower 90 in order to serve as a water heat source.

During cooling operation (solid arrows in FIG. 8), the gaseous refrigerant is introduced into the compressor 37 and compressed. The compressed refrigerant is introduced into the heat source heat exchanger unit 31′ via the first refrigerant piping connections 42, 35 and a refrigerant piping 76. The refrigerant passes the refrigerant circuit portion of the water-refrigerant heat exchanger 5′ of the heat source heat exchanger unit 31′, whereby the refrigerant is condensed (the water-refrigerant heat exchanger 5′ functions as a condenser). Hence, heat is transferred to the water passing through the water circuit portion of the water-refrigerant heat exchanger 5′. The expansion valve 33 is entirely opened to avoid high pressure drops during cooling. Then, the refrigerant flows into the compressor unit 32 via the third refrigerant piping connections 34, 43 and refrigerant piping.

The water circulates through the water circuit, which includes the cooling tower 90 and the water circuit portion of the water-refrigerant heat exchanger 5′. At the cooling tower 90, the circulating water releases heat to be cooled.

Regarding installation, the heat source heat exchanger unit 31′ can be disposed in the ceiling of a space to be conditioned whereas the cooling tower 90 may be arranged on the roof of the building, for example.

For heating operation, a boiler equipment (not shown) to heat the circulating water may be employed instead of or in addition to the cooling tower 90. 

1. A compressor unit for an air conditioner comprising: a compressor disposed in a first casing; and first and second heat source heat exchanger unit ports configured to connect the compressor unit to a heat source heat exchanger of at least one heat source heat exchanger unit of the air conditioner, the heat source heat exchanger being disposed in a second casing separate from the first casing and being configured to exchange heat with a heat source; first and second indoor unit ports configured to connect the compressor unit to an indoor heat exchanger of at least one indoor unit of the air conditioner; a first refrigerant piping fluidly connecting the first heat source heat exchanger unit port and the first indoor unit port; and a sub-cooling heat exchanger disposed inside the first casing and fluidly connected to the first refrigerant piping for heat transfer with the refrigerant to be flown through the first refrigerant piping.
 2. The compressor unit according to claim 1, further comprising: a second refrigerant piping fluidly connecting the second heat source heat exchanger unit port and the second indoor unit port, the compressor and a 4-way valve being interposed between the second heat source heat exchanger unit port and the second indoor unit port in the second refrigerant piping; and a bypass passage connected to the second refrigerant piping at a suction side of the compressor between the compressor and the 4-way valve, the sub-cooling heat exchanger being fluidly connected to the bypass passage for heat transfer between refrigerant flowing in the bypass passage and refrigerant flowing in the first refrigerant piping.
 3. The compressor unit according to claim 1, wherein the compressor unit does not comprise a main expansion valve of the air conditioner.
 4. The compressor unit according to claim 1, further comprising an oil separator located at a discharge side of the compressor between the compressor and a 4-way valve.
 5. A heat source unit for an air conditioner, comprising: a compressor unit according to claim 1; and a heat source heat exchanger unit having a heat source heat exchanger, the heat source heat exchanger being disposed in a second casing separate from the first casing and being configured to exchange heat with a heat source, wherein the heat source heat exchanger unit is fluidly connected to the compressor unit via the first and second heat source heat exchanger unit ports.
 6. The heat source unit according to claim 5, wherein a main expansion valve of the air conditioner is disposed in the second casing.
 7. An air conditioner having a heat source unit according to claim 5, wherein at least one indoor unit is fluidly connected to the compressor unit via the first and second indoor unit ports.
 8. The compressor unit according to claim 2, wherein the compressor unit does not comprise a main expansion valve of the air conditioner.
 9. The compressor unit according to claim 2, further comprising an oil separator located at a discharge side of the compressor between the compressor and a 4-way valve.
 10. The compressor unit according to claim 3, further comprising an oil separator located at a discharge side of the compressor between the compressor and a 4-way valve.
 11. A heat source unit for an air conditioner, comprising: a compressor unit according to claim 2; and a heat source heat exchanger unit having a heat source heat exchanger, the heat source heat exchanger being disposed in a second casing separate from the first casing and being configured to exchange heat with a heat source, wherein the heat source heat exchanger unit is fluidly connected to the compressor unit via the first and second heat source heat exchanger unit ports.
 12. A heat source unit for an air conditioner, comprising: a compressor unit according to claim 3; and a heat source heat exchanger unit having a heat source heat exchanger, the heat source heat exchanger being disposed in a second casing separate from the first casing and being configured to exchange heat with a heat source, wherein the heat source heat exchanger unit is fluidly connected to the compressor unit via the first and second heat source heat exchanger unit ports.
 13. A heat source unit for an air conditioner, comprising: a compressor unit according to claim 4; and a heat source heat exchanger unit having a heat source heat exchanger, the heat source heat exchanger being disposed in a second casing separate from the first casing and being configured to exchange heat with a heat source, wherein the heat source heat exchanger unit is fluidly connected to the compressor unit via the first and second heat source heat exchanger unit ports.
 14. The heat source unit according to claim 11, wherein a main expansion valve of the air conditioner is disposed in the second casing.
 15. The heat source unit according to claim 12, wherein a main expansion valve of the air conditioner is disposed in the second casing.
 16. The heat source unit according to claim 13, wherein a main expansion valve of the air conditioner is disposed in the second casing.
 17. An air conditioner having a heat source unit according to claim 11, wherein at least one indoor unit is fluidly connected to the compressor unit via the first and second indoor unit ports.
 18. An air conditioner having a heat source unit according to claim 12, wherein at least one indoor unit is fluidly connected to the compressor unit via the first and second indoor unit ports.
 19. An air conditioner having a heat source unit according to claim 13, wherein at least one indoor unit is fluidly connected to the compressor unit via the first and second indoor unit ports.
 20. An air conditioner having a heat source unit according to claim 6, wherein at least one indoor unit is fluidly connected to the compressor unit via the first and second indoor unit ports. 